-
本文基于Wind/WAVES和STEREO/SWAVES等多卫星射电观测资料, 选择第24太阳活动周2007年1月至2015年12月期间77个II型射电暴样本事件, 拟合其激波速度, 分析了激波参数与日冕物质抛射(CME)、耀斑和太阳高能粒子(SEP)等参数的相关关系及变化规律, 并探讨了射电增强对这些关系的影响. 研究结果显示: 1)在II型射电暴十米百米(DH)波段范围起始时刻, 激波高度比CME前沿高度略高一点, 即激波脱体距离(standoff distance)约0.4 Rs, 且这个高度随CME向外传播而增大. 在低日冕和高日冕, 激波脱体距离随CME速度的变化呈现明显相反的规律; 在低高度上, CME速度快, 激波脱体距离大, 而在高高度上, CME速度慢, 脱体距离大. 2)射电增强伴随事件的CME速度明显大于无射电增强事件; 射电增强伴随事件的激波速度与CME质量、动能的相关性明显好于无射电增强伴随事件. 3)有射电增强伴随的II型射电暴DH波段持续时间与CME速度、质量、动能之间无明显相关性, 而无射电增强事件的DH波段持续时间与这三个量之间呈正相关. 4)产生SEP事件的激波速度明显大于未产生SEP事件的激波速度; 有射电增强伴随的II型射电暴(激波)事件产生SEP事件的比例略高于无射电增强事件(73.5% > 67.4%), 但射电增强事件产生大SEP事件(large SEP event)的比例(67.6%)明显高于无射电增强事件(37.2%). 进一步表明, II型射电暴射电增强可作为其驱动源(激波)大概率产生大SEP事件的辨别信号之一.In this paper, we investigate 77 type-II radio burst events' data observed by Wind/WAVES and STEREO/SWAVES from January 2007 to December 2015. By fitting the frequency-time profile to obtain the corresponding shock velocity, we study the relationship between the parameters of shock and those of coronal mass ejection (CME), solar flare and the associated SEP events, and explore the influences of type II radio enhancement on these relationships. Our findings are as follows. 1) In general, at the onset time of type II radio bursts within deca-hectometric (DH) waveband, the shock front is about 0.4Rs ahead of the leading edge of CME (shock standoff distance), and this distance increases as the CME propagates outward. In the low and high corona, the relationship between shock standoff distance and CME speed indicates a significant difference; the shock standoff distance is correlated with the CME speed positively at the low altitude, but negatively at high altitude. 2) The CME speed of the events with radio enhancement is significantly larger than that with no radio enhancement; and comparing with the events with no radio enhancement, the correlation coefficient between the shock speed and the mass and kinetic energy of the associated CME is significantly high for the events with radio enhancement. 3) There is no correlation between the duration of type II radio burst in DH waveband with enhancement and the speed, mass and kinetic energy of CME. However, it presents a positive correlation for the events with no radio enhancement. 4) Usually the speed of shock that can produce SEP event is obviously higher than that with producing no SEP event. The probability of the SEP generated by the events associated with radio enhancement is slightly higher than with no radio enhancement (73.5% > 67.4%), but for the large SEP events, the generation probability (67.6%) associated with radio enhancement is about one-order of magnitude higher than that with no radio enhancement (37.2%). This conclusion indicates that the type II radio enhancement can be used as one of the signatures of the shock or the radio source that more probably produces a large SEP event.
[1] [2] [3] [4] [5] [6] [7] [8] [9] [10] [11] [12] [13] [14] [15] [16] [17] [18] [19] [20] [21] [22] [23] [24] [25] [26] [27] [28] [29] [30] [31] [32] [33] [34] [35] [36] [37] -
[1] [2] [3] [4] [5] [6] [7] [8] [9] [10] [11] [12] [13] [14] [15] [16] [17] [18] [19] [20] [21] [22] [23] [24] [25] [26] [27] [28] [29] [30] [31] [32] [33] [34] [35] [36] [37]
下载:
计量
- 文章访问数:5630
- PDF下载量:42
- 被引次数:0